/* ------------------------------------------------------------------------- *  * A Monte Carlo simulation of the dice game Craps.                          *  *                                                                           *  * Name              : craps.c                                               *  * Author            : Steve Park & Dave Geyer                               *  * Language          : ANSI C                                                *  * Latest Revision   : 9-16-95                                               *  * Compile with      : gcc craps.c rng.c                                     * * ------------------------------------------------------------------------- */#include <stdio.h>#include "rng.h"#define N 10000L                           /* number of replications *//* global variables */long    i;                                 /* replication index    */long    point;                             /* the initial roll     */long    result;                            /* 0 = lose, 1 = win    */long    wins = 0;                          /* number of wins       */double  p;                                 /* probability estimate *//* ============================== */  long Equilikely(long a, long b)          /* use a < b *//* ============================== */{  return(a + (long) ((b - a + 1) * Random()));}/* ============== */  long Roll(void)/* ============== */{  return(Equilikely(1, 6) + Equilikely(1, 6));}/* ==================== */                 /* roll until a 7 is obtained */  long Play(long point)                    /*  - then return a 0         *//* ==================== */                 /* or the point is made       */{                                          /*  - then return a 1         */  long sum;                                                                                          do {                                              sum = Roll();  } while ((sum != point) && (sum != 7));  return( (sum == point) ? 1 : 0 );}/* ============= */  int main(void)/* ============= */{  PutSeed(0);  for (i = 0; i < N; i++) {                /* do N Monte Carlo replications */    point = Roll();                                  switch(point) {      case  7:      case 11:  result = 1;                break;      case  2:      case  3:      case 12:  result = 0;                break;      case  4:      case  5:      case  6:      case  8:      case  9:      case 10:  result = Play(point);                break;    }    wins += result;  }  p = (double) wins / (double) N;          /* estimate the probability */  printf("\nfor %ld replications\n", N);  printf("the estimated probability of winning is %5.3lf\n\n", p);  return(0);}